Jet Streams 1 



By R. Lee 



Meteorological Service of Canada 

 Department of Transport 



[With one plate] 

 INTRODUCTION 



On April 1, 1954, three United States Navy F-9F fighters streaked 

 across the United States on a cross-country flight. The lead plane 

 of the trio unofficially broke the speed record with a flight time of 3 

 hours and 45 minutes, assisted by tailwinds as high as 170 m. p. h. 

 Spectacular as the flight was, an even more remarkable aspect of it 

 remained unpublicized for, before the flight took off, Lieutenant 

 Dickson, Navy meteorologist, estimated the flight time to be 3 hours 

 and 41 minutes! The takeoff time and route were deliberately 

 planned to take advantage of the jet stream high in the upper tropo- 

 sphere. About 15 years ago, the possibility of such a flight would 

 have belonged to the realm of fancy, yet today such feats of planning 

 and flying are accepted as commonplace by the men who fly our 

 modern jet aircraft. 



Let us look for a moment at the phenomenon which made this flight 

 possible — the jet stream. In a sense, the accumulation of knowledge 

 leading up to this successful forecast began as early as 1933, when 

 V. Bjerknes, J. Bjerknes, H. Salberg, and T. Bergeron first gave 

 evidence for the existence of jet streams in their classic textbook, 

 "Physikalische Hydrodynamik." Eleven years later, in 1944, Pro- 

 fessor Willett of the Massachusetts Institute of Technology published 

 a paper showing a jet stream, but it was not until the closing phases 

 of World War II in the Pacific that its practical importance be- 

 came widely recognized. As the scene of operations in the Pacific 

 Theater shifted northward in 1944 and 1945, United States high- 

 altitude bombers began to report westerly winds of up to 250 knots 



1 Reprinted by permission from The Roundel, Royal Canadian Air Force, 

 Victoria Island, Ottawa, Canada. 



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